The present invention relates to a hydraulic. diaphragm valve for regulating the flow of fluids, which has been improved in determined structural features thereof, for the purpose of achieving optimal regulation of the flow of fluid passing through it. To this end, the pertinent valve body contains a semi-conical deflector element with its upper part terminated in an open flat face the perimeter of which has the form of an isosceles triangle, the cross section of this being approximately equal to that of the valve passage according to its nominal diameter, because the passage of water through the valve takes place within said triangular section. When the valve is fully open, the streamlined form of the semiconical deflector favours the circulation of the fluid, both in the intake and in the discharge area, avoiding the occurrence of turbulence in the flow and reducing the headlosses in the valve. The valve also includes diaphragm flat in shape in its seating zone, adapting to the sides of the discharge section in order to achieve fluid leak-tightness when it is partially or totally shut.
In the most commonly employed design of known hydraulic diaphragm valves, the flexible diaphragm itself takes the form of a hemispherical or spherical shell which, for carrying out the shutting action, is seated on an area shaped like a segment of a circumference.
The shutting of the valve is carried out by injecting water under pressure into the chamber formed by the cover of the valve and the diaphragm itself, the leak-tightness of the seal being assured, in some cases, by means of one or more springs located in said chamber, which compress the diaphragm against its seating, even when the fluid pressure is low.
The opening of the valve is carried out by draining the water held in the chamber, thereby permitting the diaphragm to be deformed, leaving the fluid passage free.
The operation of the valve described here above, corresponds to the valve operating in full-on or full-off mode. For its utilisation as a regulator, in a known process it is usually fitted with pilot valves (small hydraulic valves) which, by means of sensors that compare the pressure of the fluid at the valve outlet with the pilot setting, cause the partial filling or emptying of the valve chamber, communicating it with the intake or the outflow of the fluid respectively, whereby the diaphragm adopts intermediate positions between that of totally open or totally shut.
However, the behaviour of these valves as regulators, is only acceptable within a range of flow rates around the nominal value, since when the flow rates conveyed are less than nominal, the equilibrium position of the diaphragm is not attained, which leads to serious oscillations in the pressure it is intended to regulate, because the variation in the passage cross section takes place in an alternating manner that is frequent, fast and abrupt.
The aim of the invention which constitutes the object of this Patent, consists in eliminating the problems of deficient regulating capacity of known hydraulic diaphragm valves, as described here above, by means of an improved design of the shutting mechanism, which optimises its hydraulic properties.
The body of the valve contains a semi-conical deflector element, with its axis arranged in the longitudinal direction, the upper part of which has an open flat face and the perimeter of which has the shape of an isosceles triangle of straight or mixed sides, the cross section of the latter being approximately equal to that of the valve passage according to its nominal diameter, because the passage of water through the valve takes place within the triangular section.
The vertices of the semi-cone and of the triangular opening are oriented towards the intake part of the fluid to the valve.
When the valve is fully open, the streamlined form of the semi-conical deflector favours the circulation of the fluid, both in the intake and in the discharge zone, avoiding the occurrence of turbulence in the flow and reducing the loss of head in the valve.
The diaphragm is flat in form in its seating zone, adapting to the sides of the discharge section in order to achieve the fluid leak-tightness when partially or totally shut; and it is preferentially fabricated with an elastomer of sufficient flexibility to permit the continual deformations that its operation requires, it being possible to incorporate internal reinforcement if deemed necessary for the working pressure of the valve.
The working of the valve as an operational element, in a xe2x80x9cfull-on or full-offxe2x80x9d regime, is as follows:
When the cavity comprised between the diaphragm and the cover of the valve (that is, its chamber) is filled with fluid at a pressure equal to or greater than the intake level, valve shut-off takes place, since the diaphragm is applied to its seating on the flat face of the semi-cone, covering the triangular opening.
On the other hand, when the chamber of the valve is totally drained, its complete opening is produced, since the diaphragm is deformed leaving the totality of the triangular passage section free, which is equivalent to that of the discharge pipe, of the nominal diameter of the valve.
The operation of the valve as a fluid flow regulator is the following:
At an intermediate point of the regulation process, the valve shall be partly open, the chamber partly full of fluid and the diaphragm deformed with a double-curve profile.
As the intake pressure is always greater than the discharge pressure in order that the fluid flows in the direction planned, the pressure of the fluid contained in the chamber shall be intermediate between both, and shall tend to apply the diaphragm against its seating, this force being the greater as the larger is the actuating area, for which reason the area of the diaphragm that shall be applied initially against its seating shall be that corresponding to the base of the triangular opening, and the passage section which is left free shall be that corresponding to the vertex of said opening.
Reciprocally, the intake pressure shall tend to lift the diaphragm from its seating starting with the zone of least resistance, that is, with the vertex of the triangular discharge section.
Thus, the actuation of the valve in shutting or reduction of flow shall be from back to front, starting with the higher flow rates; and the reverse in the process of opening or increase of flow.
The automatic regulation of the fluid intake and discharge pressures, which leads to automation in the actuation of the valve, is achieved by taking their respective values which are detected by a pilot valve which acts through its sensor as control and regulation organ.
In any case, the situations of hydrodynamic equilibrium assumed and described above, are produced indistinctly with passage sections close to the outermost vertex of the triangular flat face or close to its base; that is, with flow-through rates of magnitude less than the nominal value for the valve, or with flow rates close to said nominal value, respectively.
In this way, the valve can operate effectively as a regulator, in much wider flow ranges than those of conventional valves, and avoid the problems of pressure fluctuations which the latter present.